Suitability of Enset Fiber with Coffee Husk Ash as Soil Stabilizer

Expansive soil is problematic soil due to swelling and shrinkage behavior during moisture variation. Damages to shallow foundations like pavement and the footings of residential houses occurred due to these soils. Different scholars deal with stabilizing expansive soils using different mechanisms. This study also evaluated the suitability of Enset fiber with coffee husk ash materials to improve the expansive property of soils found in Jimma town. Different geotechnical parameters were determined for vargin soil and coffee husk ash with vargin soil. After treating the natural soil with varying percentages of coffee husk ash (5%, 10%, 15%, and 20%), the optimum levels of coffee husk ash were determined. Different laboratory tests such as CBR value, compaction test, and atterbertg limits were determined using the optimum coffee husk ash with varying percentages of enset fiber (0.3%, 0.6%, 0.9%, and 1.2%). The study reveals that the addition of coffee husk ash with enset fiber significantly increases the shear strength of expansive soils. With the addition of 15% of coffee husk ash and 0.9% of enset fiber, all the tested geotechnical parameters improved the expansive soils to be used as subgrade materials. The soil changed from highly swell material to poorly swell material. Therefore, it can be concluded that the reuse of agricultural wastes of coffee husk ash with enset fiber is applicable for expansive soil stebilization since it can improve the engineering strength of expansive soils and it is an economic and environmentally friendly material.